/*
 * Copyright (C) 2012 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtIncompatible;
import com.google.errorprone.annotations.DoNotMock;

import java.util.Collection;
import java.util.Map;
import java.util.Map.Entry;
import java.util.NoSuchElementException;
import javax.annotation.CheckForNull;

/**
 * A mapping from disjoint nonempty ranges to non-null values. Queries look up the value associated
 * with the range (if any) that contains a specified key.
 *
 * <p>In contrast to {@link RangeSet}, no "coalescing" is done of {@linkplain
 * Range#isConnected(Range) connected} ranges, even if they are mapped to the same value.
 *
 * @author Louis Wasserman
 * @since 14.0
 */
@Beta
@DoNotMock("Use ImmutableRangeMap or TreeRangeMap")
@GwtIncompatible
@ElementTypesAreNonnullByDefault
public interface RangeMap<K extends Comparable, V>
{
    /*
     * TODO(cpovirk): These docs sometimes say "map" and sometimes say "range map." Pick one, or at
     * least decide on a policy for when to use which.
     */

    /**
     * Returns the value associated with the specified key, or {@code null} if there is no such value.
     *
     * <p>Specifically, if any range in this range map contains the specified key, the value
     * associated with that range is returned.
     */
    @CheckForNull
    V get(K key);

    /**
     * Returns the range containing this key and its associated value, if such a range is present in
     * the range map, or {@code null} otherwise.
     */
    @CheckForNull
    Entry<Range<K>, V> getEntry(K key);

    /**
     * Returns the minimal range {@linkplain Range#encloses(Range) enclosing} the ranges in this
     * {@code RangeMap}.
     *
     * @throws NoSuchElementException if this range map is empty
     */
    Range<K> span();

    /**
     * Maps a range to a specified value (optional operation).
     *
     * <p>Specifically, after a call to {@code put(range, value)}, if {@link
     * Range#contains(Comparable) range.contains(k)}, then {@link #get(Comparable) get(k)} will return
     * {@code value}.
     *
     * <p>If {@code range} {@linkplain Range#isEmpty() is empty}, then this is a no-op.
     */
    void put(Range<K> range, V value);

    /**
     * Maps a range to a specified value, coalescing this range with any existing ranges with the same
     * value that are {@linkplain Range#isConnected connected} to this range.
     *
     * <p>The behavior of {@link #get(Comparable) get(k)} after calling this method is identical to
     * the behavior described in {@link #put(Range, Object) put(range, value)}, however the ranges
     * returned from {@link #asMapOfRanges} will be different if there were existing entries which
     * connect to the given range and value.
     *
     * <p>Even if the input range is empty, if it is connected on both sides by ranges mapped to the
     * same value those two ranges will be coalesced.
     *
     * <p><b>Note:</b> coalescing requires calling {@code .equals()} on any connected values, which
     * may be expensive depending on the value type. Using this method on range maps with large values
     * such as {@link Collection} types is discouraged.
     *
     * @since 22.0
     */
    void putCoalescing(Range<K> range, V value);

    /**
     * Puts all the associations from {@code rangeMap} into this range map (optional operation).
     */
    void putAll(RangeMap<K, V> rangeMap);

    /**
     * Removes all associations from this range map (optional operation).
     */
    void clear();

    /**
     * Removes all associations from this range map in the specified range (optional operation).
     *
     * <p>If {@code !range.contains(k)}, {@link #get(Comparable) get(k)} will return the same result
     * before and after a call to {@code remove(range)}. If {@code range.contains(k)}, then after a
     * call to {@code remove(range)}, {@code get(k)} will return {@code null}.
     */
    void remove(Range<K> range);

    /**
     * Returns a view of this range map as an unmodifiable {@code Map<Range<K>, V>}. Modifications to
     * this range map are guaranteed to read through to the returned {@code Map}.
     *
     * <p>The returned {@code Map} iterates over entries in ascending order of the bounds of the
     * {@code Range} entries.
     *
     * <p>It is guaranteed that no empty ranges will be in the returned {@code Map}.
     */
    Map<Range<K>, V> asMapOfRanges();

    /**
     * Returns a view of this range map as an unmodifiable {@code Map<Range<K>, V>}. Modifications to
     * this range map are guaranteed to read through to the returned {@code Map}.
     *
     * <p>The returned {@code Map} iterates over entries in descending order of the bounds of the
     * {@code Range} entries.
     *
     * <p>It is guaranteed that no empty ranges will be in the returned {@code Map}.
     *
     * @since 19.0
     */
    Map<Range<K>, V> asDescendingMapOfRanges();

    /**
     * Returns a view of the part of this range map that intersects with {@code range}.
     *
     * <p>For example, if {@code rangeMap} had the entries {@code [1, 5] => "foo", (6, 8) => "bar",
     * (10, ∞) => "baz"} then {@code rangeMap.subRangeMap(Range.open(3, 12))} would return a range map
     * with the entries {@code (3, 5] => "foo", (6, 8) => "bar", (10, 12) => "baz"}.
     *
     * <p>The returned range map supports all optional operations that this range map supports, except
     * for {@code asMapOfRanges().iterator().remove()}.
     *
     * <p>The returned range map will throw an {@link IllegalArgumentException} on an attempt to
     * insert a range not {@linkplain Range#encloses(Range) enclosed} by {@code range}.
     */
    // TODO(cpovirk): Consider documenting that IAE on the various methods that can throw it.
    RangeMap<K, V> subRangeMap(Range<K> range);

    /**
     * Returns {@code true} if {@code obj} is another {@code RangeMap} that has an equivalent {@link
     * #asMapOfRanges()}.
     */
    @Override
    boolean equals(@CheckForNull Object o);

    /**
     * Returns {@code asMapOfRanges().hashCode()}.
     */
    @Override
    int hashCode();

    /**
     * Returns a readable string representation of this range map.
     */
    @Override
    String toString();
}
